gecko-dev/browser/components/shell/test/browser_633221.js

ChromeUtils.import("resource:///modules/ShellService.jsm");

function test() {
  ShellService.setDefaultBrowser(true, false);
  ok(ShellService.isDefaultBrowser(true, false), "we got here and are the default browser");
  ok(ShellService.isDefaultBrowser(true, true), "we got here and are the default browser");
}